Method and apparatus for electrolytically treating metal surfaces



Dec. 5, 1950 c. w. HANGOSKY 2,532,907

METHOD AND APPARATUS FOR ELECTROLYTICALLY TREATING METAL SURFACES FiledSept. 18, 1946 3 Sheets-Sheet 1 I I! a": 6 35- 27 ii A? 3 46 i 8 l f9 155 is l :7 i l v 22 Dec. 5, 1950 Filed Sept. 18, 1946 W. HANGOSKY METHODAND APPARATUS FOR ELECTROLYTICALLY TREATING METAL SURFACES 5Sheets-Sheet 2 1950 c. w. HANGOSKY 2,532,907

METHOD AND APPARATUS FOR ELECTROLYTICALLY TREATINGMETAL SURFACES 5Sheets-Sheet 3 Filed Sept. 18) 1946 Patented Dec. 5, 1950 UNITED STATESPATENT OFFICE METHOD AND APPARATUS FOR ELECTRO- LYTICALLY TREATING METALSURFACES Clarence W. Hangoskyfllast Lansing, Mich.

Application September 18, 1946, Serial No. 697,765

26 Claims. 1

My invention relates to the electrolytic processing of metal surfaceswith special reference to preparation for microscopic examination and isdirected to a method, apparatus and electrolytic solution for suchsurface treatment, and. is a continuation-in-part of my copendinapplication Serial No. 548,841 filed August 10, 1944 (now abandoned).

Ordinarily the preparation of a specimen for metallurgical examinationunder a microscope involves the grinding of the surface withincreasingly finer grades of abrasive until the desired polish isobtained. The specimen is then etched by immersion in a suitable reagentto produce the desired etched surface for examination under themicroscope. The process requires a great deal of time and care and, evenwith skilled operators, consistent results are not always obtainable.Electrolytic methods of polishing and etching metallurgical samples havebeen the subject of considerable investigation since the processpotentially offers a rapid and reproducible means of obtaining a highquality polished and etched metallurgical specimen in a very shortperiod of time employing relatively unskilled labor.

However, difficulties have been encountered in the application of theprocess. For example, the solutions employed in electrolytic polishingand etching are quite often corrosive, inflammable, and, in someinstances, explosive, as for example, certain of the perchloric acidelectrolytes. The apparatus heretofore employed has usually required theservices of a highly skilled operator and has been relatively expensiveand bulky. The potential reproducibility of the process has not beenrealized due to shortcomings in the apparatus. Employing the prior artapparatuses, the surfaces of the specimen will be found to be Wavy and,in many instances, burned or pitted.

An object, therefore, of this invention, is to provide a process andapparatus that will consistently and rapidly reproduce on'metallurigcalspecimens, or other metal surfaces, excellent etched and/or polishedsurfaces even when the apparatus is operated by relatively unskilledworkmen.

Perchloric acid solutions, while hazardous, are highly desirableelectrolytes for many purposes and it is an additional object of myinvention to provide a metal etchin and/or polishing device in whichsubstantiall any electrolyte, specifically including perchloric acidsolutions, may be safely employed.

Since perchloric acid electrolytes are among the most diificult tohandle, the following detain of electrolyte.

2 scription-will be largely confined to such material, knowing that suchdisclosure will furnish adequate guidance for others in the employmentof similar or other solutions.

Many of the electrolytic solutions customarily employed have a lowconductivity which results in the generation of considerable heat by thepassage of electric current sometimes to the point of possible or evenactual ignition or combustion of the solution. In addition, theexcessive heat, if not dissipated promptly, adversely affects thesurface under treatment. Another object of my invention is therefore toprovide means for rapidly dissipating from the electrolyte and the metalobject being treated both the heat and gas bubbles formed during theprocess.

Further objects include the provision of an apparatus of the typedescribed which can safely handle hazardous solutions, is relativelyinexpensive and compact, which is suitable for substantially all metals,and which can be adapted for the polishing and/or etching of other metalshapes.

Briefly, I attain these and other objectives by providing an apparatusin which a relatively flat crested, gently flowing fountain of asuitable electrolyte from a closely adjacent orifice is directed againsta predetermined portion of the surface of a suitably supportedmetallurgical specimen in such manner that an even flow of electrolyteis produced. This condition having been established, the metal specimenis made the anode, or if alternating current is employed, an electrodeof a circuit which includes the foun- The heat and bubbles generated bthe electrolytic action as well as other matter which may be included inthe solution are evenly distributed and rapidly eliminated from thesurface of the sample by the flow of electrolyte. When the currentdensity employed during the flow of electrolyte is relatively high, thesurface of the metal is polished while lower current densities willproduce an etched surface. The time required to either etch or polish aspeci men is negligible compared to that required when mechanicalprocesses are employed and the results obtained by my method andapparatus are of consistently high quality, the waviness, pitting, andburning which usually characterizes electrolytic polishing or etchingbeing substantially absent. My compact and inexpensive apparatus permitsthe safe use of hazardous solutions such as those incorporatingperchloric acid (H0104) since the constant flow of electrolyte cools thesolution and the metal parts and, furthermore.

the system is enclosed in such manner as to limit the force and effectof a possible fire or explosion, it bein understood that further safetyfeatures are incorporated to prevent the possible occurrence of either.

By modifying my apparatus I can provide means for passing metal objectssuch as rods, tubes, bars, strips or wires through a continuouslyflowing jet of electrolyte thereby obtaining a highly satisfactorypolish or, alternatively, by providing a stencil of insulatin material Imay etch or polish sections of the surface or a metal specimen toproduce a decorative design. For a more detailed description, referenceis made to the accompanying specification and drawings in which:

Figure l is a side elevation of certain. parts of my apparatus;

Figure 2 is an enlarged sectional view of a portion of Figure 1;

Figure 3 is a Wirin diagram of anelectrical arrangement that may beemployed;

Figure 4 is a perspective view of a compact self-contained apparatus forpracticing the invention;

Figure 5 is a fragmentary section showing how a portion of Figure 2 maybe modified;

Figure 8 shows by way of example a that may be produced on a metalsurface by invention;

Figures 7 and 8 are face views of required for producing the desgnFigure 6;

Figure 9 is a sectional view indicating how the structure in Figure 2may be modified for electrolytically polishing elongated objects;

Figure 10 is a sectional. view indicating how aportion of the apparatusin Figure 2 may be modified;

Figure 11 is a top view of a further modification of a portion of theapparatus illustrated in Figure 2;

Figure 12 is a secion of Figure 11 taken along the line Iii-l 2; and

stencil means illustrated. in

Figure 13 is an enlarged section illustrating more clearly the featuresshown in Figure 12.

The apparatus shown in the drawings is suggested for the preferredpractice of the invention.

The parts of the apparatus shown in Figure 1 include a processingchamber generally designated l0, an expansion chamber I! connected withthe processing chamber by a duct l2, both chambers being supported by anupper horizontal wall means generally designated l5 for releasablyclamping a metal sample in position for processing, an electrolytereservoir [8 located below the processing chamber and connected theretoby a drainage tube H, and a centrifugal pump it driven by a motor 2b,the pump having its intake side connected with the reservoir It by arubber tube 2| and having its. ouimut side connected with the processingchamber It by a rubber tube 22.

The processing chamber HF, as best shown in Figure 2, includes an innerreceptacle and also includes an outer casing 26, the purpose of which isto support the inner receptacle and to serve as a safeguard againstaccidents or breakage. The inner receptacle 25 may be made of somesuitable metal as indicated in the drawing, for example, lead or astainless alley, or alternatively may be formed of glass or porcelain.The outer casing 25, which may be of stainless sheet metal, is flangedfor attachment by screws 2'! to the underside of the wall I 3 and has alarge central bottom opening 28. The inner receptacle 25 is closed atthe bot torn by a large plug to of synthetic rubber, or other suitablematerial which will not be afiectecl by the electrolyte, which coversthe opening 28 in the bottom of the casing 2t and serves to support theinner receptacle 25. At the upper end or" the receptacle 25 an innerflange 32 supports a Wall, or stage, generally designed 33, having acentral aperture 35. This upper wall not only closes the upper end ofthe processing chamber but also is adapted to support asample S of metalto be treated, the metal being positioned over the opening over theaperture Obviously such an apertured wall may be a side Wall rather thana top wall or the processing chamber, but I have found that the bestresults will be obtained where the apertured wall constitutes. the topwall of the chamber. In the preferred practice of my invent'on the areaof the aperture 35 and, therefore, the area of the sample which will beprocessed is approximately '78 sq. mm. The upper wall 33 may comprise alayer of glass 3-5 resting on a suitable gasket 3"! together with anupper layer 33 of synthetic rubber or other su'table material ofresilient character for sea ing contact with the sample S.

In the particular construction shown, the previously mentioned duct I2is integral with the. inner receptacle 25, extends through suitablerubber bushings 39, and turns upward in the expansion chamber 1 I. Sinceit is desirable that inflammable or explosive vapors be confined to theinterior of the processing chamber 25 and preeluded from. the expansionchamber H, suitablemeans are employed to out off the expansion chamberexcept in emergencies signalized by pressure rise. in the processingchamber. To this end, I may employ a barrier that will yield or break inresponse to pressure rise. Thus in Figure 2 a disc 40 of very thin micaor other frangible material is shown in position to close the end of theduct l2, the disc being held in place by a suitable retaining bushing4|. Whenever a disc 40 is ruptured by an excessive pressure rise, ahand-hole cover 42 is removed from the expansion chamber for access toreplace the disc.

Preferably the clamping means [-5 is designed for quick retaining andreleasing operation and is al o designed to serve as a contactor makingelectrical connection with the sample S, it being contemplated that thesample will serve as an electrode in the electrolytic process. Theillustrated clamping means I 5 includes a post 45 that is fixed to thehorizontal wall I3 and is suitably connected to a circuit wire 45.Slidingly mounted on the post 45 is a metal block or collar 4! that maybe adjustably retained at various positions by a thumb screw 48. Aresilient arm or leaf sprin 5 3 of stainless steel or the like extendsoutwardly from the block 41 and carries at its outer end a suit blesleeve 5| into which is threaded a manually adjustable screw 52. Thebottom of the screw makes a ball-and-socket connection with a suitablecontact block 5-3 for exerting pressure against the sample S. The block53 may be stainless steel.

The tube 22 extending upwardly to the processing chamber it! from thepump i8 is part of a passage means that in the preferred practice of myinvention is adapted to project a fountain of electrolyte against thesurface of the sample S at the processing aperture 35, and it iscontemplated that the interior of this passage means will be providedwith a metal surface to serve ordinaril as the cathode in a directcurrent electrolytic circuit, or an electrode in an alternating 5.current circuit. In the preferred practice of my invention I provide therequired interior metal surface by using a suitable metal for a portionof the passage means. To this end the rubber tube is connected to thelower end of a cathode tube 55 of lead, stainless steel or othersuitable material extending upwardly in sealing engagement with therubber plug 30. A circuit wire 55 is shown connected to a terminal 51 onthe lower portion of the cathode tube 55. The upper end of the cathodetube 55 is provided with a shoulder 59 adapted to receive and supportconcentrically a tube of insulating material such as glass. As shownmore clearly in Figure 5, the internal diameter of the glass tube 58 issomewhat greater than the minimum diameter of the processing aperture 35and extends upwardly almost into contact with the walls of the aperture,the purpose being to conduct the electrolyte to the surface of thesample without imparting more than the minimum velocity necessary'toattain this objective. It is essential for best results that the crestof the fountain formed by the electrolyte emerging from the tube 58assume as closely as possible a substantially flat configuration asshown at C in Figure 5. By relatively flat is meant a crest that issmoothed-surfaced and convex and preferably with the apex of the crestnot substantially greater than one-quarter of an inch above the top ofthe supporting stage.

It is believed that the walls of the processing aperture 35 tend toremove from the fountain the slow moving external sections of the liquidfountain returning them to the container 25, and permitting only thecentral portion of the fountain having a substantially constant velocityin every portion to contact the sample.

To assist in obtaining a relatively flat crest on the fountain atransverse screen 60 of material such as glass may be disposed adjacentthe upper end of the insulating tube 58, although the provision of suchscreen is optional. The screen 50 may be of conventional mesh form, and,if formed of conductive material such as metal, may be electricallyconnected to the cathode 55.

A suitable glass tube '6! also extends through the plug 30 and isconnected to the drainage tube ll to drain material from the receptacle25 into the reservoir or storage vessel Hi. It should be noted that thecathode member 55 is movably held by the plug 30. If desired, control ofthe current may be obtained by varying the distance between the sample Sand the upper end of the metal cathode 55 particularly if theelectrolyte has a high resistance. However, I prefer to provide othermeans of regulating the current, since regulation by means of electrodespacing requires an adjustment of the height of the insulating tube 53and greater reproducibility will be obtained if the electrode spacing isheld con stant for each type of metal.

The manner in which the apparatus described to this point operates maybe readily understood. A sample to be electrolytically processed issecured by the clamping means 15 in position covering and sealing theaperture 35. The desired clamping pressure may be attained by varyingthe flexure of the leaf spring either by adjustment of the collar M orby adjustment of the screw 52. The operator then closes the circuit ofthe motor 20 to energize the pump l3 whereupon electrolyte from thereservoir it flows upwardly through the tube 22 and the cathode tube 55and is directed through the insulating tube 58 as a foun- 6 tain to theundersurface of the sample S. Upon contacting the sample S, the liquidmovingat a low but uniform velocity and presenting a rela-. tivelyconstant velocity in cross section mushrooms outwardly across the faceof the sample contacting it evenly and sweeping away bubbles generatedin the electrolyte. 'The electrolyte dropping away from the fountain tothe bottom of the inner receptacle 25 drains into the tube IT for returnto the reservoir E6, the capacity of the return drain arrangement beingsufficient to prevent any substantial rise in the liquid level in theprocessing chamber. When physical circulation of the liquid isestablished, the electrolytic circuit is closed to obtain a flow ofelectric current between the sample S and the cathode tube 55 throughthe liquid fountain. When the electrolytic action has been carried farenough, the operator in sequence opens the electric circuit,de-energizes the motor 26, and then removes the sample S.

It will be noted that the processing chamber, and in fact the completecircuit of the electrolyte, is completely enclosedand is sealed forprotection of the operator as well as to limit any possible evaporationof the solution. Any infiam-- mable or explosive vapors incidental tothe procedure will be confined to'the processing chamber; Shouldaccidental ignition in the processing chamber occur to create ahazardous pressure rise, the safety disk as will rupture to permit thegases from the processing chamber to be released into the expansionchamber H in such manner as to safeguard the-operator. The ignitionhazard exists only in'the processing chamber and it is important to notethat in the described mode of operation, only a small portion of thevolume of electrolyte employed is present in the processing chamber atany given time. Such an arrangement makes it possible to employ therelatively large body of electrolyte without correspondingly great risk.Certain factors may be noted as important in keeping the temperature ofthe electrolyte down to a safe and practical range. One factor is theuse of a relatively large body of electrolyte to absorb the generatedheat. ()ther factors are the cooling effect of the fountain ofelectrolyte in the processing chamber and the cooling means provided bytheeleotrolyte reservoir l6 and the connecting tubes H, 2| and 22. "Thecathode, of course, tends to remain at a relatively lowtemperaturebecause of the flow of cool electrolyte therethrough. The;fountain of electrolyte, by being maintained at a lower temperature, notonly cools the metal sample but also rapidly conducts heat therefromthereby'preventing burning of the sample and decomposition of theelectrolyte. It may also be noted that control of the sha e and velocityof the fountain and its crest contributes largely tothe production ofplanar surfaces, and to the elimination of wavine's's which ischaracteristically present in electrolytic samples etched by other knownapparatuses.

An important advantage of my invention is that it may be practiced withan exceptionally convenient electrical arrangement such as thatindicated by the wiring diagram in-Figure 3and which may be embodied ina compact. self-contained, and inexpensive apparatus such as'that shownin Figure 4. v 5 The particular electrical arrangement shown in Figure 3incorporates aplurality of circuits that may be usedselectively' forenergizing the previously mentioned anode Wire 46 andcathode wire 55with D. 0. current for electrolytic polishing, or for energizing thewires with D. C. current for electrolytic etching, or for energizing thewires with A. C. current for electrolytic etc-hing.

The main leads 55 and 65 in Figure 3, which are adapted for plugginginto any suitable A, C. source, are controlled by a main switch 57 andare shunted by a suitable lamp 58 to indicate the closed position of theswitch. The main leads 65 and 56 are connected by wires '53 and "ii bothto the primary of a transformer 39 and to the coil of a normally opensafety relay l2 controlled by a safety switch 73. The secondary of thetransformer 6'5 is in series both with the coil of a second normallyopen safety relay E5 and with the sample S and cathode 55. Thecontactors of the two safety relays l2 and '55 are connected in serieswith the previously mentioned anode wire 5-5 and with anarnmeter H.

The main leads 65 and 66 are connected also by wires ES and 85 with thepreviously mentioned motor 2% for driving the pump 48, the motor beingin series with a motor switch 85 and the coil of an indicating relay 82.The purpose of the relay is to control a lamp 83 for signalizing pumpoperation.

In the preferred practice of my invention a timer T is employed toprovide precise processing intervals and the timer is connected with themain leads Iii-and 58 by wires 85 and 85, the timer being in series withboth a timer switch 81 and the coil of a normally open relay 88controlling an indicator lamp 9|]. The timer exercises control of theprocesses through a normally open timer relay 5 I, one contact of whichis connected to the previously mentioned cathode Wire 56.

The A. (1. processing circuit is traced as follows: main lead 65, acontrol rheostat 92, one blade of a double-.polesingle-throw switch 93,a wire 95, the contractor of the timer relay 9i, cathode wire 56,cathode 55, the stream or jet of electrolyte, the metal sample S,.anodewire 46, the contactor of relay 15, the contactor of relay #2, ammeter11, a wire 96, the coil of a normally open indicating relay 9!controlling an indicating lamp 98, and the second blade of switch 93 tothe second main lead 66. Preferably a voltmeter I is placed in shunt, asshown, to indicate the voltage adjustment of the rheostat 92.

To provide D. C. current in the apparatus, I prefer to use some suitablerectifier means instead of a motor-generator set. For example, I mayemploy a single mercury rectifier tube II of a suitable type. The twomain leads 65 and 5B are connected to a transformer I02 for heating thecathode of the mercury tube WI and are also connected to the primary ofa transformer I03, a wire I05 being provided for this purpose.Prefer'ably the primary of the transformer we is adjustable relative tothe number of turns energized, the wire I55 being connected to a slidingcontact I56.

One side of the secondary of the transformer I03 is connected by a wireI52 with the same side of the contactor of the timer relay 9| as thepreviously mentioned wire 95 and the other side of the secondary isconnected by a wire I08 with the cathode of the rectifier tube IBI.

The D. C. circuit for electrolytic polishing is traced as follows: thesecondary of the transformer I03, wire I 08 to the rectifier cathode,wire H3 from the plate of the rectifier, a polish-control rheostat II I,wire H2, the coil of a normally open indicating relay II-3 forcontrolling an indicating lamp H4, 9. switch II5, a wire I-I6, am-

meter 17, contactors of relays I2 and 15, anode wire 45, sample S, theelectrolytic stream, cathode 55, cathode wire 56, the contactor of timerrelay 9|, and wire :IOI back to the transformer secondary. Preferably avoltmeter II! shunts the two wires H2 and In! to indicate the voltagesetting of the rheostat III.

To provide a parallel D. C. etching circuit, a wire H8 connects wireIII} with an etch-control rheostat I20, a wire I-2I connects therheostat with the coil of a normally open indicating relay I22 forcontrolling an indicating lamp I23, and the relay coil is connected tothe previously mentioned wire H6 through a switch I25. The voltmeter IZBacross the wires IZIand I01 indicates the voltage setting of therheostat H0.

The compact apparatus in Figure 4, which may for example beapproximately three feet high, has a housing or cabinet I80, the upperwall of which is the previously mentioned wall I3 for supporting theconcealed processing chamber I0 and the expansion chamber II. Thecabinet I30 may be provided with a suitable door I3I for access to theinterior when desired. At the rear edge of the top wall I3 is aninclined instrument panel I32.

On the instrument panel I32 is a suitable knob I33 for intervaladjustment of the timer '1', and knob I35 for adjusting the contact I 55of the transformer I33. In addition the panel I32 has the followingdevices that have been previously mentioned: main power input switch 51,main switch indicating light 68, pump switch 8I, pump indicating light53, ammeter ll, voltmeter II! for the D. C. polishing circuit, voltmeterI25 for the D. C. etching circuit, voltmeter I55 for the A. C. etchingcircuit, rheostat Ill for the D. C. polishing circuit, rheostat I25 forthe D. C. etching circuit, rheostat 92 for the A. C. etching circuit,indicating lamp Ild for the D. C. polishing circuit, indicating lamp I23for the D. C. etching circuit, and indicating lamp 53 for the A. C.etching circuit.

On the cabinet top IS in Figure 4 is the clamping means 35 forreleasably retaining a metal sample over the aperture 35 of theprocessing chamber, the hand-hole cover 52 for the expansion chamber,timer switch 8's in the form of a push button, safety switch 1'3 also inthe form of a push button, D. C. polishing switch H5, D. C. etchingswitch I25, and A. C. etching switch 93. The cabinet top I3 may also beprovided with a water fountain I36 for the convenience of the operator,the fountain being used to wash metal sample surfaces before and afterelectrolytic processing as required.

The manner of using a compact apparatus constructed as indicated byFigures 3 and 4 will be readily apparent. The operator manipulates theclamping means I5 to secure the metal sample over the aperture of theprocessing chamber as heretofore described, adjusts the polishingrheostat l I I if the reading of the voltmeter il'. indicates adjustmentshould be made, closes the switch 8% to start the pump, closes the D. 3.polishing switch H5, adjusts the timer T by means of the knob I33 forwhatever time interval is desired, presses the button safety switch '13with one hand and presses the timer button switch 3? with the otherhand.

It is to be noted that the two switch buttons 13 and $7 are spaced toofar apart to be manipulated simultaneously by one hand, the purpose ofsuch spacing being to require both hands of the operator and therebymake it impossible for the operator to inadvertently touch the clampingmeans i while exposed conducting material of the clamping means isenergized by electric current.

A relay 15 controlled by the electrolytic jet prevents closing of thepolishing or etching cir- Quits in the absence of a stream ofelectrolyte from the pump I8 which electrolyte furnishes a currentconducting connection between the cathode 55 and the sample S and servesas a safeguard against the creation of an arc in the process chamber 25,which might result in fire or explosion, or damage to the sample as bypitting. The ammeter 11 indicates the amperage of whatever electrolyticcircuit is employed.

When the timer light 91! goes out to indicate the end of thepredetermined interval of polishing, the operator may immediately etchthe sample without removing the sample from the apparatus. I havediscovered that many materials may be etched simply by continuing theelectrolytic process very briefly with substantially reduced voltage andamperage. It is necessary merely for the operator to open the D. C.polish switch H5, close the D. C. etch switch 125, adjust the rheostat120 guided by the voltmeter i26, adjust the timer '1 for the shorterprocessing period, and then again close the push button switches 13 and81. When the timer breaks the circuit at the end of the desired etchingperiod, the sample may be released from the clamping means I5 andbriefly washed at the water fountain I36.

If desired, the three switches 93, H5 and I25 may be biased by springaction to open position and require manual pressure for closing. In suchcase, the switch 13 is omitted since the two switches H5 and I25 servethe safety feature of requiring use of one of the operators hands.

In some instances etching with an A. C. current instead of D. C. currentis desirable. In such event, guided by the voltmeter let, the operatorsets the rheostat 92, adjusts the timer, closes the double-pole switch93, and depresses the two push button switches 13 and 81. If it isdesirable to employ chemical etching, the sample will, of course, beremoved from the apparatus at the end of the polishing interval.

While various electrolytic solutions may be employed in variouspractices of my invention, I prefer to use a mixture includingperchloric acid and a suitable alcohol. Nearly any kind of alcohol willbe found satisfactory. Preferably water is added primarily to increasethe conductivity of the mixture, ordinary tap water being preferred overdistilled water.

As an example of a preferred electrolytic formula, I may employ thefollowing:

800 cc. of methyl alcohol with 3% ether 146 cc. of tap water 54 cc. ofperchloric acid (70-72% concentration) Another electrolytic solution,adapted for use in polishing stainless steel, is sulfuric acid 15%,phosphoric acid 63%, and water 22%.

In employing the described apparatus and the preferred solution forelectrolytically processing a metal surface of approximately 78 sq. mm.,the cathode tube is adjusted to space the metal of the cathode tube 55approximately 1% inches plus or minus of an inch from the surface of thesample S and the electrolyte is maintained at a temperature below 90 F.The glass or insulating tube 58 extends upwardly to within approximatelymm. of the wall of the processing aperture 35. A supply of 12 or morequarts of electrolyte is placed in the reservoir it andthe electrolyteis pumped through the cathode tube 55 at approximately 1 quart perminute, the rate of flow being controlled to yield a fountain having arelatively flat crest which projects upwardly beyond the upper surfaceof the outer wall 33 of the processing chamber from A; to A of an inchwhen the sample S is not in place. Preferably the power adjustmentpermits a range of current up to 10 amperes and independently a range upto 300 volts potential, it being understood that this can be variedeither by the apparatus or by a movement of the oathode 55 when requiredby the circumstances.

It should be understood that the above values are given merely toillustrate preferred and satisfactory practices, and should not beconstrued as absolute or limiting values.

D. C. current of from 2 to 3 amperes at 175 to 200 volts may be used forthe electrolytic polishing of various types of steel. For most of thealuminum alloys, D. C. current of 2.5 to 4 amperes may be employed atthe same voltage. For brass or bronze alloys the amperage should beraised to the range of 2.5 to 5 amperes. Pure copper, pure nickel, pureiron and other metals in pure state can be successfully polished byvarying the current values within the given ranges. With few exceptionsthe values mentioned result in polished surfaces. To etch steel, directcurrent of 0.5 to 0.75 ampere at approximately 38 volts may be used, orinstead, alternating current of only a fraction of an ampere may be usedat to 220 volts.

The high current values recited above and the high resistance of theelectrolytic solution result in the generation of considerable heatwhich if not adequately dissipated results in burned or pitted metalsurfaces. The described method of circulating the electrolyte withspecial reference to the projection of a fountain of the solutionagainst the sample effectively dissipates the generated heat and keepsthe sample surface cool. The mushrooming of the liquid stream againstthe metal surface carries away gases released in the process andprevents the formation of any appreciable number of retained bubbles onthe metal surface.

The electrolytic polishing may require from 8 to 30 seconds and thesubsequent etching only a fractionof a second. The entire procedure ofpolishing and etching a sample may be cut down to as low as 10 seconds.The time required for mounting and dismounting the sample is negliible.

An important advantage of my process is that additional time is savedover prior art procedures since the sample need not be finely ground inpreparation for electrolytic polishing. Heretofore it has been a commonpractice to carry a sample through a number of preparatory operationsprior to the polishing step, a typical series of operations includingsemi-rough grinding, successive hand-sanding on successive abrasivebelts, and lapping on one or two lapping wheels, the whole preparatoryprocedure requiring say twenty minutes. In contrast, a sample may beprepared for my polishing procedure in a single operation with an '30mesh abrasive belt, or with a rubber wheel.

The described apparatus is so simple in operation and incorporates somany safeguards that a person of no technical skill can learn to operatethe apparatus'rapidly and efiiciently withless.

than five minutes of instruction. The standards of a research polish maybe attained by a novice repeatedly because of the controlledconditionsinherent in the operation of the apparatus. The controlconditions are important not only for insuring good results but also forinsuring uniform results for any number of samples. Since apparatusfactors are constant including the processing area, the path ofelectrolytic current, the volume and rate of flow of the electrolyte,the amperage and voltage of current, and the process intervals, thehuman equation is entirely eliminated. For a large run of samples of agiven character, no adjustments of the rheostats are necessary so thatthe procedure narrows down to merely the operation of switches withperhaps adjustment of the timer when electrolytic etching' followselectrolytic polishing. By keeping a record of the adjustments employedfor various runs of samples, given procedures may be readily duplicatedand standards of procedure established.

In general, the current flow through the electrolyte at a givenpotential will vary with the proportion of perchloric acid and will varyalso with the proportion of the water content. Thus the current at agiven potential dropped to 0.3 ampere when the electrolyte comprised 99%alcohol and 1% perchloric acid with no water present. At the samepotential 3.0 amperes of current passed through an electrolytecomprising 40% alcohol, 20% perchloric acid and 40% water. At lowalcohol content, however, considerable gas is released and pitting ofthe samples is likely to occur, both for aluminum and steel samples. Arelatively high proportion of alcohol increases the resistivity of theelectrolyte but minimizes gas formation and reduces the possibility ofpitting. Electrolytic solutions of high alcohol content work well notonly on steel and aluminum but also on bronze.

While employing an electrolytic solution with the perchloric acid ashigh as 20% by volume of the solution produces excellent results, such asolution is so highly corrosive that for the sake of the operator aperchloric acid concentration of approximately 5% is ordinarilypreferred. Raising the perchloric acid content above 5% causes the metalto be removed faster and in special instances may produce desirableresults that cannot be obtained at lower acid concentrations. Forextremely accurate Work, however, mixtures of low acid content and highalcohol content are indicated.

While the described wiring diagram incorporates a single timer for threedifierent circuits, namely, a D. C. circuit for polishing, a D. C.circuit for etching and an A. C. circuit for etching, obviously separatetimers for the different circuits may be employed. Since a polishingoperation extends over several seconds while an etching operationrequires only a fraction of a second, such separate timers may bespecialized for the particular time ranges involved. The use of separatetimers for the difierent circuits will eliminate the necessity for timeradjustment every time a change is made from one circuit to another.

The purpose of Figure is to indicate how the described apparatus may bemodified by using a mechanical arrangement for operating the relay I6.In the arrangement shown in Figure 10, it is contemplated that a leverI40 responsive to the flow of the electrolyte will open and close aswitch indicated in dotted lines at I39, controlling the safety relay15, the switch being substituted 12 for the low voltage circuit throughthe sample and cathode 55.

In the particular arrangement shown in Figure 10, a relatively shortcathode tube MI in a processing chamber I42 carries the previouslymentioned glass extension 58 directed towards the processing aperture 35in the wall 33 as previously described.

Surrounding the cathode tube MI is a movable receptacle I 55, thereceptacle being cup-shaped with a bottom aperture I46 surrounding thecathode tube. The receptacle I 35 is carried by the previously mentionedlever I65 and the lever in turn is carried by a shaft I 31. The shaft I41 extends through the chamber wall and is operatively connected to theswitch I39.

The lever I46 is suitably biased towards an upper position either bygravity or spring loading but the bias is overcome by loading thereceptacle M5 with electrolyte. In the absence of electrolyte flow, thecup is in the upper position shown in full lines in Figure 10. When theelectrolyte begins the flow at a rate sufficient to contact the sample,it drops from the sample into the receptacle I 15 at a rate greater thanelectrolyte can drain from the receptacle through the annular clearancebetween the cathode tube I GI and the receptacle aperture I46.Consequently the liquid level in the receptacle I45 rises and the leverM9 is weighed down to close the switch I39. Upon the cessation ofelectrolyte flow against the sample, the receptacle I45 drains quicklyto permit the lever I40 to rise and. thereby open the switch I39.

Either the low voltage control circuit of Figure 3 or the alternativeswitch arrangement of Figure 10 serves the important function ofminimizing fire hazard. The preferred electrolyte is so highlyinflammable that any arcing will start violent combustion.

Figure 5 indicates how the structure in Figure 2 may be modified bysubstituting a wall, or stage generally designated I58, for thepreviously described wall or stage 33. The substituted wall I56 may bein the form of a glass plate having a central aperture I5I to expose asample S to electrolytic action. The glass plate is additionallyapertured to provide one or more drainage ports I52 positioned away fromthe sample S, preferably four such ports being provided.

It is contemplated that a small portion of the fluid from the stream ofelectrolyte impinging on the sample at the aperture I5I will flowradially outward over the outer surface of the glass plate to return tothe interior of the processing chamber 25 through the drainage ports I52. The outer surface of the glass plate may be roughened to permitfluid to how radially outward between the bottom surface of the sampleand the upper surface of the glass plate, or channels I54 extendingradially outwardly from the processing aperture may be formed in theupper surface of the glass plate for similar purpose. Under someconditions such radial flow to the outer drainage ports is desirable toprevent a gas pocket from forming in the aperture I5I. As in otherforms, the minimum diameter of the aperture I5I should be less than theinternal diameter of the tube 58.

It will be noted that Figure 5 illustrates an approximation of thedesired shape of the crest C- of the foundation of electrolyte shownwith the sample S removed. A slight convexity, such as that illustrated,has not been found objectionable, but every efiort must be made toapproach l3 a plane crest. This is best attained through the use of lowvelocities and the use of aperture walls to remove the outer sections ofthe fountain. Failure to control the shape of the crest, or use ofrelatively high velocities, Will result in inconsistent and usuallyunsatisfactory results.

Figure 9 indicates how the structure shown in Figure 2 may be modifiedto serve as means for electrolytically polishing or otherwiseelectrolytically treating elongated objects, such as wires, rods,strips, bars or tubes. The particular. arrangement shown is designed forelectrolytically polishing a metal rod R.

v Figure 9 shows an inner receptacle I55 corresponding to the innerreceptacle 25 of Figure 2. The inner receptacle I55 defining theprocessing chamber has a removable cover generally designated I56 in theform of an inverted cup having a radial flange 151 for bolting to theinner receptacle I55. Such a co er member may be fabricated from glass.The cover I58 has two coaxial apertures ltd and I65 to slidingly receivethe rod R so that a shifting portion of the rod may be enclosed forelectrolytic processing. Preferably the two apertures I68 and ISI areprovided with rubber bushings M2 to minimize the escape of electrolytefrom the interior of the processing chamber. Preferably the radialflange I51 is formed with an annular rib 563 to provide an annulardrainage groove I85 for collecting any electrolyte that may escapethrough the apertures I66 and IGI, the collected electrolyte drainingback into the processing chamber through one or more drainage ports I66.

Mounted inside the cover IE8 of the processing chamber is a T-shapedpassage member it'i of lead, stainless steel or other suitable material,the end of the passage member surrounding the aperture ltii. The body orstem of the T-shaped passage member 161 is shown telescoped. over thereduced upper end of a metal cathode H58 corresponding to the previouslydescribed metal cathode 55 in Figure 2. For connecting the rod E into acircuit as anode, a suitable brush I18 is provided for contact with therod at a suitable location. The rest of the apparatus, suggested byFigure 9, is constructed as shown in Figure 2.

The manner in which a length of rod R is electrolytically processed bymeans of the apparatus shown in Figure 9 may be readily understood fromthe above description. The rod is shifted progressively through the twoapertures 55% and GI in the direction indicated by the arrow while astream of electrolyte is pumped upward into the T-shaped passage memberlEl and while electric current is flowing between the metal wall of thepassage-member It? and the enclosed rod R, the current flowing throughthe stream of electrolyte.

Figures 5, '7 and 8 indicate how my method and apparatus may be employedto apply designs to metal surfaces, which designs may be ornamental ormay be in the form of letters or numbers. The design shown in Figure 6,for example, is a formal or conventional design for a flower having adark center ill and light petals lit.

The first step in applying the design shown in Figure 6 is to replacethe wall 33 of Figure 2 with a wall 113 (Figure '7) that differs fromwall 33 only in having a plurality of radially positioned apertures H5instead of the single central aperture 35. The radial apertures Iconform to the areas of the petals I12 of the desired design. The metalsurface to be decorated is placed against the outside surface of thewall I13 and the areas of the metal surface at the radial apertures I15are electrolytically polished in the manner heretofore described.

After the polishing operation is completed to produce the pattern oflight-colored petals I12, the metal surface is removed and a wall I16(Figure 8) is substituted for the wall I13, the wall I155 having asingle central aperture I11 of the same configuration as the dark centerI1I of the design. The metal article to be decorated is then placedagainst the outer surface of the wall I15 with the aperture I11concentric to the previously applied light petals I12. The metal surfaceof the object to be decorated is then subjected to a brief etchingoperation through the aperture I1! in the manner heretofore described.As a result, the metal surface will have the design shown in Figure 6,the areas of the petals 12 being lighter than the untreated metalsurface and the center I1I of the design being darker than the untreatedmetal.

In some practices of my invention for applying designs to metalsurfaces, anodic dyes may be employed, the metal surface being treatedor processed electrolytically and dyed. By employing successivestencils, as explained above,- multicolor designs may be obtained.

Figures l1, l2 and 13 illustrate a modified form of sample-supportingwall for the container 25 and in this modification comprises a generallycircular disk I88 of glass having an axially disposed frusto-conicalprocessing aperture IN, the uppermost portion of which may becylindrical as shown at 82. A second disk I83 of glass, or similarmaterial, is secured to the rear face of the disk i8ll by a suitablecement and has formed therein an opening I86 adapted to register withthe opening I8I. The lower portion of the opening I86 is generallycylindrical while the upper portion is conical forming an extension ofthe walls of the aperture I8I. Either the lower face of the disk I orthe upper face of the disk I83 has formed therein a plurality of groovesI8 5 extending radially from the aperture I8! or the opening I86 formingconduits which communicate with a plurality of discharge ports I85extending through the lower disk I83. Thus it may be seen that thegrooves I84 constitute internal conduits properly disposed to rapidlyconduct used electrolyte, together with accumulated gas bubbles, fromthe surface of a sample disposed over the aperture I81. It isunderstood, of course, that the insulating tubea58 extends upwardly into'the opening I86 approximately to the end 'of the cylindrical section insuch manner that a small quantity of electrolyte will be permitted toflow between the lips of the tube 58 and the opening I86. If desired,the disk I80 may be provided with a facing of resilient material such asrubber similar to that previously described. The effect of thisstructure is to permit a somewhat increased flow of electrolyte sinceits ability to dispose of bubbles formed in the process is somewhatgreater than is the case of other forms of supporting walls hereinbeforeillustrated.

The preferred practice of my invention set forth in specific detailherein for the purpose of disclosure will suggest to those skilled inthe art various changes and substitutions under my basic concept and Ireserve the right to all such departures from my description thatproperly lie within the scope of mv appended claims.

I claim:

1. In an apparatusfor electrolytically treating a surface of metal, asupport having, an aperture therein defining the portion of the surfaceof the object to be treated, means for directing a solid. column ofelectrolyte through the aperture against the surface of the object, saidmeans including a, conduit having a discharge orifice somewhat widerthan the said aperture-defining surface and also including anelectrolyte discharge zone for removing an external portion of the saidstream prior to its contacting the said surface, a cathode in contactwith the electrolyte, means for establishing an electrical circuitincluding the cathode, the object, and the electrolyte, and meansincluding grooves formed in a surface of the support extending radiallyfrom said aperture for conducting electrolyte from the surface beingtreated, said conduit being substantially vertically positioned inalignment with the aperture over which said object is supported.

2. In an apparatus for electrolytically treating a surface of a metalobject, a wall adapted to support the object on one side thereof, saidwall having an aperture and a plurality of radially disposed internalchannels extending from the aperture to the other side of the wall,means including a conduit having a discharge orifice somewhat wider thanthe said aperture for projecting electrolyte through the aperture in theform of a smooth surfaced column into contact with the metal object, anda cathode in contact with the electrolyte whereby electrolyte isconducted uniformly and rapidly from the surface of the object, saidconduit being substantially vertically positioned in alignment with theaperture over which said object is supported.

3. In an apparatus for electrolytically treating the surface of, a metalobject, a wall adapted to support the object, said wall. having anaperture and a plurality of grooves radiating from i said aperture andterminating in drain openings extending through said wall, conduit meansfor projecting electrolyte through the aperture in the form of asmooth-surfaced column into contact with the metal object, and a cathodein contact with the electrolyte whereby electrolyte is conducteduniformly and rapidly from the surface of the object, said conduit meansbeing substantially vertically positioned in alignment with the apertureover which said object is supported.

4. In apparatus for electrolytically treating a surface of a metalobject, a substantially horizontal support of substantial thicknesshaving an aperture therein over which the object is placed, and whichaperture defines the surface of the object to be treated, said aperturebeing enlarged from below, a nozzle extending into the enlarged lowerpart of the aperture with clearance thereabout, and means for projectinga low velocity non-particulated stream of electrolyte upwardly throughthe nozzle into contact with the exposed surface of the object, thecross-sectional area of the stream being substantially as great as thearea of the surface to be treated said clearance between the nozzle andthe aperture permitting excess electrolyte to flow away from the objectand be recaptured.

5. In apparatus for electrolytically treating the surface of a metalobject, the combination of a stage adapted to support the object andhaving an aperture therein defining the surface of the object to betreated, a nozzle in substantial alignment with the aperture fordelivering a stream of electrolyte to said surface, said stage having atleast one laterally extending passage communicating with said aperturefor carrying away electrolyte after contacting the metal surface.

6. In apparatus for electrolytically treating a surface of a metalobject, a substantially horizontal support of substantial thicknesshaving an aperture therein over which the object is supported, and whichaperture defines the surface of the object to be treated, a nozzle insubstantial alignment with said aperture and in close proximity thereto,means for delivering a.

solid stream of electrolyte upwardly through the nozzle into contactwith the exposed surface of the object, the cross-sectional area of thestream being substantially as great as the area of the surface to betreated, and radial passages in the. support communicating with theaperture for conducting away electrolyte.

I. In apparatus for electrolytically treating a surface of a metalobject, a substantially horizontal support of substantial thicknesshaving an aperture therein over which the object is placed, and whichaperture defines the surface of the object to be treated, with saidaperture being enlarged from below, a nozzle extending into the enlargedlower portion of the aperture with clearance therebetween, said nozzlehaving a discharge orifice coaxial with but of greater cross-sectionalarea than the exposed area of the surface of said object, and means fordelivering a low velocity non-particulated stream of electrolyteupwardly through said nozzle into contact with said surface, theenlarged nozzle orifice in conjunction with the clearance between thenozzle and the wall of said aperture causing the outer annular portionof the upwardly moving stream to be sheared from the stream, thereby tohave that portion of the stream which contacts said surfacecharacterized by substantially uniform velocity throughout itscrosssectional area and by having a substantially flat crest in freeflow.

8. In apparatus for electrolytically treating a surface of a metalobject, a horizontal support of substantial thickness having an aperturetherein over which the object is placed, and which aperture defines thesurface of the object to be treated, with said aperture being enlargedfrom below, a nozzle extending into the enlarged lower portion of theaperture with clearance therebetween, said nozzle having a dischargeorifice coaxial with but of greater crosssectional area than the exposedarea of the surface of said object, and means for delivering a lowvelocity non-particulated stream of electrolyte upwardly through saidnozzle into contact with said surface, the enlarged nozzle orifice inconjunction with the clearance between the nozzle and the wall of saidaperture causing the outer annular portion of the upwardly moving streamto be sheared from the stream, thereby to have that portion of thestream which contacts said surface characterized by substantiallyuniform velocity throughout its cross-sectional area and by having asubstantially flat crest in free flow, and lateral passages in thesupport communicating with the aperture for conducting away electrolytewhich does not escape through said clearance.

9. In apparatus for electrolytically treating a surface of a metalobject, a substantially horizontal support having an aperture thereinover which the object is placed, and which aperture defines the surfaceof the object to be treated, a nozzle in substantial alignment with saidaperture, and positioned in close proximity to said surface, means forprojecting a low velocity non-particulated stream of electrolyteupwardly through the nozzle into con tact with the exposed surface ofthe object, and a, fine mesh screen in the nozzle for imparting to thestream substantially uniform crss-sectional velocity, the velocity ofthe stream and the size of said mesh being such that the projectedstream maintains its non-particulated character as it contacts theobject being treated.

10. Themethod of anodically removing metal from the surface of a metalobject which comprises the steps of moving a non-particulated column ofelectrolyte upwardly through an opening in a horizontal stage towardsaid object, controlling the flow of the electrolyte in said column sothat in the absence of the object,

the crest extends above the top surface of the stage and ischaracterized by having a smoothsurfaced, convex form, contacting theobject with said stream, removing electrolyte which has contacted theobject by conducting it radially outwardly, and passing electric currentthrough said stream with said object connected as anode.

11. The method of anodically removing metal from the surface of a metalobject which comprises the steps of moving a non-particulated column ofelectrolyte upwardly through an opening in a horizontal stage towardsaid object, controlling the flow of the electrolyte in said column sothat in the absence of the object, the crest extends above the topsurface of the stage and is characterized by having a smoothsurfaced,convex form, adjusting the velocity of said column so that in theabsence of the object the crest of the stream will not be substantiallygreater than one-quarter of an inch above the top surface of the stage,contacting the object with said stream, removing electrolyte which hascontacted the object by conducting it radially outwardly, and passingelectric current through said stream with said object connected asanode.

12. The method as set forth in claim 10 in which the control of theelectrolyte flow in the column is effected by removing the outerperiphery of the column.

13. The method as set forth in claim 10 in which the control of theelectrolyte flow in the column is effected by interposing a screen inthe column adjacent to said opening in the stage to thereby render moreuniform the velocity of all portions of the stream which contact saidobject.

14. In apparatus for anodically removing metal from the surface of ametal object, the combination of a substantially horizonta1 stage havinga frusto-conical, vertical opening therethrough with the larger diameterportion of the opening facing downwardly, a conduit projecting upwardlyinto the lower portion of said frustoconical openin and terminatingshort of the top surface of said stage, but having the upper end of theconduit spaced from the walls of said opening to provide a passagewaytherebetween, and means for forcing a column of electrolyte upwardlythrough said conduit with sufficient force to cause the crest of thecolumn to extend above the top surface of the stage.

15. The apparatus as set forth in claim 14 in which radial passagescommunicating with said vertical opening are formed in the stage adsetforth in claim 14 in of insulating material.

17. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a

substantially closed chamber including an apertured top wall, means forsupporting the object to. beprocessed on the exterior of said top wallover said aperture, means including a nozzle within the chamber forprojecting a solid stream of electrolyte upwardly through said apertureinto contact with the object, a cathode positioned to contact theelectrolyte While the electrolyte impinges against the object, andcircuit means for connection with said cathode and said object to causecurrent flow through said projected stream.

18. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a substantially closed chamber including anapertured top wall, means for supporting the object to be processed onthe exterior of said top wall over said aperture, means including anozzle within the chamber for projecting a solid stream of electrolyteupwardly through said aperture into contact with the object, a cathodepositioned to contact said stream before the stream impinges against theobject, and circuit means including a low voltage control circuit forapplying high voltage between said object and said cathode only when theobject and cathode are bridged by electrolyte.

19. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a substantially closed chamber including anapertured top wall, means for supporting the object to be processed onthe exterior of said top wall over said aperture, a tubular passage insaid chamber directed upwardly towards said aperture, the interior ofsaid passage being provided with a metal surface, means to cause a solidstream of electrolyte to flow through said passage thereby to form a jetof electrolyte flowing upwardly through said aperture and impinging onsaid object, and means for connection with said object and said metalsurface to form an electric circuit including said jet, said metalsurface being connected in said circuit as a cathode.

20. In an apparatus for electrolytic-ally polishing or etching thesurface of a metal object, a substantially closed chamber including anapertured top wall, means for supporting the object to be processed onthe exterior of said top wall over said aperture, a tubular passage insaid chamber directed upwardly towards said aperture, the interior ofsaid passage being provided with a metal surface, means to cause a solidstream of electrolyte to flow through said passage thereby to form a,jet of electrolyte flowin upwardly through said aperture and impingingon said object, main circuit means for connection with said object andsaid metal surface to form an electrolyzing circuit including said jet,and a, safety circuit including a relay having its contacts in serieswith the main circuit for energizing said electrolyzing circuit afterthe object and metal surface are bridged by said jet, said metal surfacebeing connected in said circuit as a cathode.

21. In an apparatus for electrolytically polishing or etching thesurface of a metal object,

a substantially closed chamber including an aper- 19 tured top wall,means for supporting the object to be processed on the exterior of saidtop wall over said aperture, a tubular passage in said chamber directedupwardly towards said aperture, the interior of said passage: beingprovided with a metal surface, means to cause a solid stream ofelectrolyte to flow through said passage thereby to form a jet ofelectrolyte flowing upwardly through said aperture and impinging on saidobject, means for connection with said object and said metal surface toform an electrolyzing circuit including said jet, a normally open switchin said circuit to prevent current flow between said object and saidmetal surface, and means to close said switch in response to jet flow ofthe electrolyte, said metal surface being connected in said circuit as acathode.

22. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a substantially closed chamber having a topwall provided with an aperture therein surrounded by insulatingmaterial, conducting means above said top wall for releasably clampingsaid object over said aperture in a position to close the aperture,means including a nozzle within the chamber for projecting a solidstream of electrolyte upwardly through said aperture into contact withthe object, a cathode positioned to contact the electrolyte while theelectrolyte impinges against the object, and circuit means forconnection with said cathode and said clamping means to cause currentflow between the cathode and the object through said projected stream.

23. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a substantially closed processing chamberineluding an apertured top wall, means for supporting the object to beprocessed on the exterior of said top wall over said aperture, meansincluding a nozzle within the processin chamber for projecting a solidstream of electrolyte upwardly through said aperture into contact withthe object, a cathode positioned to contact the electrolyte While theelectrolyte impinges against the object, circuit means for connectionwith said cathode and said object to cause current flow through saidprojected stream, and a second chamber communicating with saidprocessing chamber and separated therefrom by a frangible wall toprovide an expansion space to prevent hazardous pressure rise in saidprocessing chamber in the event of combustion therein.

24. In an apparatus for electrolytically polishing or etching thesurface of a metal object, a substantially closed chamber including anapertured top wall, means for supporting the object to be processed onthe exterior of said top wall over said aperture, means includin anozzle within the chamber for projecting a solid stream of electrolyteupwardly through said aperture into contact with the object, a cathodepositioned to contact the electrolyte while the electrolyte impingesagainst the object, and cir cult means for connection with said cathodeand said object to cause current flow through 20 said projected stream,said circuit means including a timer efiective to cause energization ofsaid circuit for time periods of predetermined duration.

25. In an apparatus for electrolytically treating metal surfaces, anapertured plate for supporting a metallic object to be treated, meanscontaining a body of electrolyte beneath said plate, means forprojecting a column of electrolyte from said body onto the exposedsurface of the object overlying the aperture in said plate, a maincircuit including said body of electrolyte, said column and said objectarranged to pass an electric current between said column and said objectacross said exposed face of the object, a, relay having contactsincluded insaid circuit for controllin the latter, and auxiliary circuitmeans actuated by the impingement of electrolyte upon said object forcontrolling said relay to close said main circuit, whereby energizationof said main circuit is dependent upon the column of electrolyte beingin contact with said object.

26. In an apparatus for electrolytically treating metal surfaces, anapertured support for an object to be treated, means for holding such anobject upon said support with a; surface of said object exposed through"said aperture, a chamber disposed beneath said support, an electrolytecontainer disposed generally below said chamber, a cathode electrodesecured by said chamber and having a passageway for electrolyte, meansfor projecting electrolyte from said container through said passageway,a shoulder on said electrode, and a conduit telescoped over saidshoulder and extending upwardly to a point adjacent the aperture in saidsupport, whereby electrolyte projected through said passageway isdirected toward the surface of said object exposed through saidaperture.

CLARENCE W. HAN GOSKY REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 820,482 Dion May 15, I906 844,262Dieterich Feb. 12, 1907 1,219,843 Mueller et al Mar. 20', 1917 1,416,929Bailey 1 May 23', I922 1,940,612 Sweeney Dec. 19, 1933 2,199,501MacBlane May' '7, 1940 2,382,735 Marks Aug. 14, 1945 FOREIGN PATENTSNumber Country Date 335,003 Great Britain Sept. 18, 1930 39,808 SwedenMar. 12, 1913 OTHER. REFERENCES Metal Progress, Aug. 1942, pages 209through 212.

Hydraulics, by King et al, (5th ed, 1948-), published by John Wiley &Sons, pages 1'76 through 178.

10. THE METHOD OF ANODICALLY REMOVING METAL FROM THE SURFACE OF METALOBJECT WHICH COMPRISES THE STEPS OF MOVING A NON-PARTICULATED COLUMN OFELECTROLYTE UPWARDLY THROUGH AN OPENING IN A HORIZONTAL STAGE TOWARDSAID OBJECT, CONTROLLING THE FLOW OF THE ELECTROLYTE IN SAID COLUMN SOTHAT IN THE ABSENCE OF THE OBJECT, THE CREST EXTENDS ABOVE THE TOPSURFACE OF THE STAGE AND IS CHARACTERIZED BY HAVING A SMOOTHSURFACED,CONVEX FORM, CONTACTING THE OBJECT WITH SAID STREAM, REMOVINGELECTROLYTE WHICH HAS CONTACTED THE OBJECT BY CONDUCTING IT RADIALLYOUTWARDLY, AND PASSING ELECTRIC CURRENT THROUGH SAID STREAM WITH SAIDOBJECT CONNECTED AS ANODE.
 14. IN APPARTUS FOR ANODICALLY REMOVING METALFROM THE SURFACE OF A METAL OBJECT, THE COMBINATION OF A LSUBSTNTIALLYHORIZONTAL STAGE HAVING A FRUSTO-CONICAL, VERTICAL OPENING THERETHROUGHWITH THE LARGER DIAMETER PORTION OF THE OPENING FACING DOWNWARDLY, ACONDUIT PROJECTING UP-